1. Field of Invention
The present invention relates to a chuck.
2. Related Prior Art
Disclosed in Taiwanese Patent M290799 is a conventional chuck. As shown in FIGS. 3 and 4 of the patent, the telescopic chuck is used to drive a bit A that includes a tip indicated by a letter “a” and a shank referred to by a letter “c.” The telescopic chuck includes a socket 20, a sleeve 30, a restraint 40, a C-clip 50 and a spring 60. The socket 20 defines a space 23 for receiving the shank of the bit A. A groove 22 is defined in an external side of the socket 20. A shoulder 33 is formed on an internal side of the sleeve 30. The sleeve 30 is movably installed on the socket 20. The C-clip 50 is disposed in the groove 22. The helical spring 60 is installed on the socket 20. A ring 43 is formed on an internal side of the restraint 40. The restraint 40 is movably installed on the socket 20. The restraint 40 is connected to the sleeve 30 by a C-clip. The sleeve 30 and the restraint 40 are kept on the socket 20 since the shoulders 33 and 43 are restrained by the C-clip 50. The spring 60 is compressed between the shoulder 43 and the C-clip 50. A magnetic ring 31 is fit in the sleeve 30 near the space 23 defined in the socket 20. As shown in FIGS. 5 and 6 of the patent, the magnetic ring 31 can be used to attract a screw 70 driven by the bit A held by the chuck. The chuck includes a complicated structure made of many elements in a lengthy process. The chuck is inevitably expensive.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.